It sounds like science fiction, but a probe has been developed that can set cancer cells aglow.

Though currently only tested on mice, researchers at the Stanford University School of Medicine have developed a molecular probe that identifies protein-destroying enzymes that exist in cancer cells.

The molecule, usually invisible to the naked eye, carries a fluorescent tag that lights up when it binds to the enzymes. The tag emits near-infrared light, which passes through the skin and can be tracked with a special camera.

The findings were published in the Sept. 9 online issue of Nature Chemical Biology.

During the study, mice with grafted tumours were given an intravenous injection of the molecular probe and were then scanned with noninvasive, whole-body imaging to show enzymatic activity.

The study points out that while many diagnostic imaging approaches have side effects, such as an increased risk of cancer, the technique takes a less-invasive approach.

"Nowadays the detection of cancer, breast cancer for instance, is normally done by mammography, using X-rays — which might actually increase your risk of cancer. We think these probes may ultimately provide a less harmful, noninvasive method of detecting cancer," said the article's lead author Galia Blum, a postdoctoral scholar in the laboratory of Matthew Bogyo, assistant professor of pathology at Stanford.

Bogyo said the next generation of experiments will apply the probes during surgery, likely by "painting" on the probe to identify cancerous tissues that could be missed.

Molecule could be used to treat Alzheimer's, arthritis

Researchers say that the size of the enzyme-targeting molecule makes it ideal for slipping across cell membranes and enter living cells. It can also move through an animal quickly, which opens up the possibility of using the technique to light up tumours while surgery is in progress.

Bogyo says that in addition to identifying cancer tumours, the probe might be useful in treating diseases such as Alzheimer's, arthritis, atherosclerosis and osteoporosis. That's because these illnesses involve protein-destroying enzymes which the probe could light up and identify.

In the meantime, more animal testing is needed before a request can be made to the U.S. Food and Drug Administration to conduct a human trial.

"Since there are currently no fluorescent imaging agents in use in humans, the approval process is likely to require significantly more preclinical data," Bogyo said.